Fix Python Binary Command Being Truncated to the First Element

[Alvaro-Kothe]

This patch basically adapts _find_installation_impl to handle a list for the name_or_path argument.

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On master using /usr/bin/env, meson setup passes when providing a wrong command, e.g.

python = ['/usr/bin/env', 'this-command-doesnt-exist']

meson setup prints Program python found: YES (/usr/bin/env).

With this patch it fails with

meson.build:3:22: ERROR: <PythonExternalProgram 'python' -> ['/usr/bin/env', 'this-command-doesnt-exist']> is not a valid python or it is missing distutils

The other case that it failed on master was running python through qemu

cross.ini

[binaries]
python = ['qemu-aarch64-static', '-L', '/home/alvaro/aarch64-root', '/home/alvaro/aarch64-root/usr/bin/python3.14']

which fails with

meson.build:3:22: ERROR: <PythonExternalProgram 'python' -> ['/usr/bin/qemu-aarch64-static']> is not a valid python or it is missing distutils

while with this patch it passes and creates the correct suffix for the python target

build foo.cpython-314-aarch64-linux-gnu.so: c_LINKER foo.cpython-314-aarch64-linux-gnu.so.p/meson-generated_foo.pyx.c.o

Closes #15985

[Alvaro-Kothe]

I will leave this into draft mode while I fix the CI errors.